With car payments, you're paying for depreciation and maintenance costs. We work on around £1-2k per year - between us we have a small car and a bigger car and drive them both according to need.
Currently the small car is likely to cost quite a bit less than that as we'll keep it until it dies, but under £1000 pa for those costs and the big vehicle, which is actually a small van, maybe slightly more but not horrendously so, say around £2.5k pa. But that means we're running two vehicles for less than the cost of your £5k pa for one. What's your plan when the finance ends? Can you keep the car without paying any more or is it one of those deals where you have the choice of paying a lump sum, carrying on payments for another car, or hand the car back and end up with nothing? If you can keep the car without a payment, that would be good as then you can run it for a while as you save up for another one and it might also free up money to go on holiday.
Car finance can be a 'not bad' option but unless you have a lot of money, you can't run a spendy car and go on holiday and have regular expensive days out and buy your lunch rather than taking leftovers and spend a lot on your appearance and eat out regularly and have lots of subscriptions and do all the other consumer things that use up money.
You have to pick and choose and prioritise and it sounds like your DHs wants are getting a lot of the priority at the moment. He's got the car payment for the expensive car, he gets all the TV subscriptions, he gets to not bother budgeting, he gets to pop to the shop for his treats whenever he likes and sod the rest of you. If he cut back even a bit of his indulgences, it would free up money so the family can go on holiday, so you need to make it clear to him that this is going to happen. It's also him that's paying a big child support payment every month but it's probably a whole other thread about whether that comes out of family money or his personal money.
Pool all your money.
Review all your expenses and cut back where possible.
Pay for essentials such as his tax, pension contributions, mortgage, bills, food, travel, all child related expenses, savings for annual and irregular expenses etc including a holiday, basically everything that is a family expense rather than you or DH personal spending.
Then split what's left 50/50 between you and him and he needs to learn to only spend his share of the budget, instead of currently what sounds like most of it.